1. Field of the Invention
The present invention relates to a chlorine-containing polymer vulcanizing composition such as represented by chlorinated polyethylene or epichlorohydrin polymer, and to a vulcanized product thereof.
2. Description of the Prior Art
Generally, a chlorine-containing polymer is widely used as a material for a rubber product or a resin product, or as a material for an adhesive or a paint because of its excellent heat resistance, oil resistance, weather resistance, ozone resistance, and abrasion resistance. In particular, chlorinated polyethylene is attracting people""s attention as a rubber material utilizing its excellent heat resistance, oil resistance, weather resistance, and ozone resistance.
Various proposals have already been made for vulcanization of chlorinated polyethylene. For example, organic peroxides and various sulphur-containing compounds such as mercaptotriazines are proposed as a vulcanizing agent for chlorinated polyethylene. It is also known to use various organic vulcanization accelerators such as an amine compound in combination with the vulcanizing agent for accelerating vulcanization of chlorinated polyethylene. It is a common knowledge of those skilled in the art that an acid receiving agent must be blended with a vulcanizing composition for absorbing an acid component generated in a small amount in vulcanizing chlorinated polyethylene. For example, Japanese Laid-open Patent Publication No. 55-39250/1980 proposes a metal compound selected from the group consisting of oxide, hydroxide, carboxylate, silicate, carbonate, phosphite, borate, basic sulfite and tribasic sulfate of a group IVA metal in the periodic table, as the acid receiving agent.
A vulcanizing composition disclosed in Japanese Laid-open Patent Publication 63-28047/1988 provides stability of a vulcanized product and a suitable vulcanization speed, and the patent publication gives oxide, hydroxide, carboxylate, silicate, carbonate, phosphite and borate of a group II metal in the periodic table, and oxide, basic phosphite, basic carbonate, basic carboxylate, basic sulfite, and tribasic sulfate of a group IVA metal in the periodic table as example of the metal compounds. Specific examples thereof include magnesia, magnesium hydroxide, barium hydroxide, magnesium carbonate, barium carbonate, slaked lime, quick lime, calcium carbonate, calcium silicate, calcium stearate, zinc stearate, calcium phthalate, magnesium phosphite, calcium phosphite, zinc white, tin oxide, litharge, red lead, white lead, dibasic lead phthalate, dibasic lead carbonate, tin stearate, basic lead phosphite, basic tin phosphite, basic lead sulfite and tribasic lead sulfate.
Japanese Laid-open Patent Publication 53-3439/1978, 54-58750/1979, 09-176433/1997, and others disclose a vulcanizing composition containing a thiadiazole compound as a vulcanizing agent for a chlorine-containing polymer, in which a basic metal oxide, a basic metal salt, a basic metal hydroxide, or the like is used as a compounding agent.
However, none of these vulcanizing compositions is a composition obtained by blending a zeolite compound as an acid receiving agent with a chlorine-containing polymer. Although these vulcanizing compositions provide vulcanized products having good vulcanization properties and are put into industrial use, they have a poor preservation stability and involves various restrictions in industrial rubber processing. For example, if the preservation stability of the vulcanizing composition is poor, vulcanization proceeds during preservation to make vulcanization molding impossible, whereby the vulcanizing composition must be discarded, desired vulcanization properties can not be obtained, or a dimension precision is greatly reduced, even though the vulcanization molding can be carried out.
Japanese Laid-open Patent Publication 58-18939/1983 discloses blending a specific aluminosilicate as a heat stabilizer with a chlorine-containing polymer. However, this does not contain a vulcanizing agent, i.e. is not one obtained by blending an aluminosilicate with a vulcanizing composition, much less gives a teaching of preservation stability of the vulcanizing composition.
Japanese Laid-open Patent Publications 07-157566/1995 and 07-286098/1995 disclose a polymer vulcanizing composition containing an epichlorohydrin polymer, a mercapto vulcanizing agent, and a hydrotalcite. However, this vulcanizing composition is not one obtained by blending a zeolite compound as an acid receiving agent.
Japanese Laid-open Patent Application 60-233138/1985 discloses a composition containing a chlorosulfonated polyolefin, an epoxy compound, and an A-type zeolite. However, this is a disclosure that the A-type zeolite preserves a white color of the chlorosulfonated polyolefin at the time of heating and increases the strength of the vulcanized product, and it also fails to give a teaching on the preservation stability of the vulcanizing composition.
In view of the above-mentioned circumstances, the object of the present invention is to provide a chlorine-containing polymer vulcanizing composition with improved preservation stability.
The inventors of the present invention have made various studies in order to solve the above problems, and found out that blending a zeolite compound as an acid receiving agent is effective in improving the preservation stability of a chlorine-containing polymer vulcanizing composition, thereby completing the present invention.
Accordingly, the present invention provides a chlorine-containing polymer vulcanizing composition obtained by blending with a chlorine-containing polymer, (a) a zeolite compound, (b) a vulcanizing agent, and (c) an optional organic vulcanization accelerator.
Further, the present invention provides a chlorine-containing polymer vulcanizing composition containing (d) an optional inorganic vulcanization accelerator in addition to the above-mentioned compounding agents (a), (b), and (c). By blending the (d) component, the vulcanization speed and the compression set can be improved.